The CFAR Behavioral Core will provide support and resources for investigative teams which collect information from human subjects. The specific aims of the Behavioral Core address two major areas: recruitment/retention of enrollees in clinical and behavioral studies and quality of assessment of behavioral risk factors, behavioral interventions, and behavioral outcomes related to HIV and AIDS. In regard to recruitment and retention of subjects, the Core is designed to 1) evaluate current methods and strategies to recruit and encourage continued participation in HIV/AIDS studies, 2) develop and test strategies for recruitment and retention of hard to reach populations, 3) assist in training individuals to serve as recruiters and outreach workers, and 4) serve as a repository for information on recruitment and retention. In regard to assessment, the Core is designed to 1) evaluate current methods of assessment, 2) develop and test now approaches to participant interviews, 3) evaluate and refine current measures of assessing adherence and sexual behavior, and 4) serve as resource center for training interviewers.